1. Field of the Invention
The present invention relates to rotary vane pumps, and is particularly concerned with high vacuum rotary vane pumps which may be simply constructed in cartridge form.
2. Background of the Invention
The construction of rotary vane pumps is wide and varied, but basically all such pumps include one or more rotors which are rotatable in a like number of eccentrically disposed, serially connected pumping chambers which define a low pressure output side of the pump.
Various techniques for improving pump operation and pumping efficiency have heretofore been devised. For example, in my earlier U.S. Pat. No. 3,782,868, entitled "Rotary Vane Pump" I disclose structure for noise free lubrication of the pump.
In present high vacuum pumps oil for lubrication and leakage sealing is permitted to enter, in fact is drawn into, the exhaust stage of a pump and, due to occluded gasses, adversely affects the pressure of the inlet stage to an intolerable degree.